JPH0977527A - Method for drawing optical fiber and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the drawing of an optical fiber, to suppress the fluctuation in the outside diameter of the optical fiber and to improve its quality while suppressing the vibration of the optical fiber by imparting the fluctuation in the tension for damping vibration in the drawing direction of the optical fiber at the time of generation of the vibration. SOLUTION: The optical fiber 3 drawn from a perform 1 is cooled down to a prescribed tap. by blowing, for example, compressed air thereto with first and second cooling units 11A, 11B before the optical fiber arrives at a primary die 4. Vibration is generated in the optical fiber in this process. This vibration is detected by a fiber vibration detector 12. On the other hand, a take-off roll 10 is vibrated in nearly synchronization with the vibration of the fiber 3 at the frequency of about twice the vibration frequency of the optical fiber 3 in the drawing direction of the optical fiber 3 by a microvibrator consisting of a piezoelectric vibrator in a take-off machine 9, by which the tensile fluctuation in the drawing direction is applied on the optical fiber and the coated optical fiber integral therewith and the vibration of the optical fiber 3 is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber drawing method and apparatus for heating an optical preform to draw an optical fiber.

[0002]

2. Description of the Related Art In drawing an optical fiber, as shown in FIG. 9, an optical fiber element wire 3 is obtained by heating a preform 1 in a heating furnace 2 and pulling it downward while melting it. The temperature of the optical fiber strand 3 obtained at this time is
Since it is a high temperature of 1800 ° C or higher, it must be cooled to 50 ° C or lower just before the primary die 4. In the primary die 4, the optical fiber element wire 3 is provided with a primary coating layer. At this time, if the temperature is high, the coating thickness of the primary coating layer will not be constant. If the temperature is too high, the phenomenon that the primary coating layer cannot be coated at all will occur.

Next, after curing the primary coating layer in the primary curing oven 5, the secondary die 6 is used to set the optical fiber element wire 1
A secondary coating layer is applied on the next coating layer. Then, the secondary coating layer is cured in the secondary curing furnace 7, and the obtained optical fiber core wire 8 is obtained.
Is taken up by the take-up roll 10 of the take-up machine 9 and taken up by a take-up machine (not shown).

The point of drawing the optical fiber in this way is to cool the optical fiber element wire 3 from about 1800 ° C. to about 50 ° C. just before the primary die 4.

Initially, the drawing speed of the optical fiber wire 3 was 10
At 0 m / min to 300 m / min, if the cooling length from the lower end of the meniscus portion 1a of the preform 1 to the primary die 4 was about 4 m, it could be sufficiently cooled in the air.

However, when the drawing speed of the optical fiber element wire 3 is required to be as high as 500 m / min, 1000 m / min, 1500 m / min, there is a limit in air cooling.

Therefore, a method has been proposed in which the circumference of the optical fiber element wire 3 is surrounded by a cooling tube, and helium gas is caused to flow into the cooling tube to cool the optical fiber element wire 3. Since helium gas has a higher heat transfer coefficient than air, it can be cooled efficiently.

However, in the method using helium gas, since the price of helium gas is high, the amount of helium gas used increases with the increase of the linear velocity of the optical fiber element wire 3, which causes the cost increase of the optical fiber. There is a point.

Therefore, a technique has also been proposed in which compressed air is blown onto the optical fiber element wire 3 to cool it. Again,
Although the amount of compressed air used increases with an increase in the linear velocity of the optical fiber strand 3, the compressed air can be formed at low cost, so that the cost increase of the optical fiber can be avoided as much as possible.

[0010]

However, as the linear velocity of the optical fiber strand 3 increases, the amount of compressed air used increases (for example, at 1000 m / min, 600 to 700 l / min of air is supplied to the optical fiber strand). 3), when the compressed air flows around the optical fiber element wire 3 at a high speed, the optical fiber element wire 3 vibrates, and when this vibration becomes large, the preform 1 is removed from the preform 1 in the heating furnace 2. The meniscus portion 1a being changed to the optical fiber element wire 3 is fluctuated, and the fluctuation of the wire diameter of the optical fiber element wire 3 becomes large, and further, there arises a problem that the optical fiber element wire 3 is broken. In this case, the vibration of the optical fiber strand 3 is usually around 10 Hz.

On the other hand, even if it is cooled by using helium gas,
A linear velocity of 1200 m / min requires a flow rate of 100 l / min,
Similar problems occur.

An object of the present invention is to provide an optical fiber drawing method capable of carrying out drawing while suppressing vibration.

[0013]

DISCLOSURE OF THE INVENTION The present invention is directed to an improved method of drawing an optical fiber by heating a preform to draw an optical fiber.

The optical fiber drawing method according to the present invention is characterized in that, when vibration of the optical fiber wire occurs, the optical fiber wire is subjected to vibration damping tension fluctuations in the drawing direction.

When the vibration damping tension variation is applied to the optical fiber strand in the drawing direction as described above, the vibration of the optical fiber strand can be suppressed. Therefore, the drawing of the optical fiber is stable, the fluctuation of the outer diameter of the optical fiber can be suppressed, and the quality of the optical fiber can be improved.

Further, in the optical fiber drawing method according to the present invention, the vibration of the optical fiber element wire is detected, and the optical fiber element wire is synchronized with the vibration so that the frequency thereof is approximately two.
It is characterized in that tension fluctuations for damping are applied in the drawing direction of the optical fiber strand at a frequency doubled.

When the tension fluctuation for damping is applied to the optical fiber strand in the drawing direction in this manner, the vibration of the optical fiber strand can be suppressed. Therefore, the drawing of the optical fiber is stable, the fluctuation of the outer diameter of the optical fiber can be suppressed, and the quality of the optical fiber can be improved.

In these cases, the fluctuation in the damping tension applied to the optical fiber strand can be provided by vibrating the take-up roll for pulling the optical fiber strand in the drawing direction.

As described above, when the take-up roll is vibrated in the drawing direction and the vibration damping tension fluctuation is applied to the optical fiber strand, the vibration damping tension fluctuation can be easily applied to the optical fiber strand.

Further, the fluctuation of the damping tension applied to the optical fiber strand can be provided by varying the rotation speed of the drive motor of the take-up machine that pulls the optical fiber strand.

When the number of rotations of the drive motor of the take-up machine is changed in this way, it is possible to easily give a tension change for damping to the optical fiber strand.

Further, the vibration fluctuation tension applied to the optical fiber strand can be applied by varying the rotation speed of the drive motor of the winder for winding the optical fiber strand.

By varying the number of rotations of the drive motor of the winding machine in this way, it is possible to easily apply a tension variation for damping to the optical fiber strand.

Further, the fluctuation of the damping tension applied to the optical fiber element wire can be applied by vibrating a die for coating the optical fiber element wire with resin in the drawing direction.

When the die for coating the resin on the optical fiber strand is changed in the drawing direction in this way, the viscosity of the resin in the die causes the vibration of the die to be transmitted to the optical fiber strand through the resin. The tension fluctuation for damping can be easily applied to the optical fiber strand.

Further, the present invention is directed to an improvement of an optical fiber drawing apparatus which heats a preform and draws it to obtain an optical fiber strand.

In the optical fiber drawing apparatus according to the present invention, a damping tension applying means for applying a vibration damping tension fluctuation to the optical fiber strand in the drawing direction, and a fiber vibration for detecting the vibration of the optical fiber strand. A detector, a computing unit that computes the frequency of the vibration damping tension fluctuation based on the detection output of the fiber vibration detector, and a driver that drives the damping tension applying means with the output of the computing unit. It is characterized by having.

With this structure, the frequency of the vibration damping tension fluctuation applied to the optical fiber strand is automatically set by the fiber vibration detector and the arithmetic unit to drive the vibration damping tension applying means. It is possible to suppress the vibration of the optical fiber strand by automatic control.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first example of an embodiment of a drawing apparatus for carrying out an optical fiber drawing method according to the present invention. The parts corresponding to those in FIG. 9 described above are designated by the same reference numerals.

In the optical fiber drawing apparatus of this example, compressed air and nitrogen (some helium gas may be mixed) between the lower end of the meniscus portion 1a of the preform 1 and the primary die 4. Alternatively, first and second cooling units 11A and 11B for blowing a gas such as helium gas to cool the optical fiber element wire 3 are provided in upper and lower two stages. These first and second cooling units 11
A fiber vibration detector 12 using a fiber position detector is arranged between A and 11B so that the vibration of the optical fiber element wire 3 can be detected. In the take-off machine 9 for taking the optical fiber core wire 8 at the end side of the drawing line,
Vibration control for vibrating the take-up roll 10 in the drawing direction of the optical fiber element wire 3 in a housing 15 that rotatably supports a rotary shaft 13 that rotates with a rotary drive source (not shown) through a bearing 14. A minute vibrating body 16 formed of a piezoelectric vibrator is provided as a tension applying means. Other configurations are the same as those in FIG. 9.

Next, an optical fiber drawing method of this embodiment using such an optical fiber drawing apparatus will be described.

In this example, before the optical fiber element wire 3 obtained by drawing from the preform 1 reaches the primary die 4, the optical fiber element wire 3 is formed in the first and second cooling units 11A and 11B, for example. Compressed air is blown to cool the optical fiber strand 3 to a predetermined temperature (for example, 50 ° C. or lower).

Vibration occurs in the optical fiber element wire 3 during the cooling process. The vibration of the optical fiber strand 3 is detected by the fiber vibration detector 12. An example of the vibration of the optical fiber strand 3 at this time is shown in FIG.

On the other hand, in the take-up machine 9, the take-up roll 10 is moved in the drawing direction of the optical fiber element wire 3 by the microvibrating body 16 made of a piezoelectric vibrator, and the frequency of the optical fiber element wire 3 is approximately 2 The optical fiber element wire 3 and the optical fiber core wire 8 integrated with the optical fiber element wire 3 are vibrated at a frequency twice as much as the frequency of the vibration. The tension for vibration damping is applied to the optical fiber strand 3 at a frequency approximately twice in the drawing direction. In this example, as shown in FIG. 3 (B), tension is applied at the midpoint A of the vibration of FIG. 3 (A), and the tension is maintained up to one peak portion B of the vibration of FIG. 3 (A). It becomes zero at the peak portion B, and tension is applied at the midpoint C of the vibration, and the tension is as shown in FIG.
(A) The vibration fluctuation tension that is continued up to the other peak portion D of the vibration (A) and becomes zero at the peak portion D is repeatedly applied in a rectangular wave shape.

In FIG. 3B, T ₁ is the tension originally applied to the optical fiber strand 3, and is 60 to 80 g when the linear velocity of the optical fiber strand 3 is 500 m / min. Further, T ₁ is the minimum value of the fluctuation in tension for damping applied to the optical fiber strand 3, T ₂ is the maximum value of the fluctuation in tension for damping, and ΔT is the magnitude of the fluctuation in tension for damping. Yes, the difference between T ₂ and T ₁ (T ₂ −T ₁ ).

Here, ΔT is preferably in the following range.

0 <(ΔT / T ₁ ) × 100% <10% When a tension fluctuation for damping is applied to the optical fiber element wire 3 and the optical fiber core wire 8 integrated with the optical fiber element wire 3 in this way, the optical fiber The vibration of the wire 3 can be suppressed. Therefore, the drawing of the optical fiber is stable, the fluctuation of the outer diameter of the optical fiber can be suppressed, and the quality of the optical fiber can be improved.

The optical fiber element wire 3 thus suppressed in vibration is passed through the primary die 4 to apply the primary coating layer, and then passed through the primary curing furnace 5 to cure the primary coating layer. Then, the optical fiber strand 3 is passed through the secondary die 6.
Secondary coating layer on the primary coating layer of
The secondary coating layer is cured by passing through the above, and the obtained optical fiber core wire 8 is taken up by a take-up roll 10 of a take-up machine 9 and taken up by a take-up machine (not shown).

An example of the first example of the above embodiment will be described.

The drawing speed of the optical fiber strand 3 is 1200 m /
min, and the wire diameter of the optical fiber wire 3 was set to 125 μ ± 0.3 μm and drawn. At this time, the total amount of compressed air supplied to the first and second cooling units 11A and 11B is 700 l / mi.
n. The optical fiber element wire 3 vibrated by 1 mm or more during cooling by blowing the compressed air. Therefore, the take-off machine 9
The take-up roll 10 of the optical fiber 3
The tension fluctuation for damping in the drawing direction of the optical fiber 3
Of about 20 to 30 μm at a frequency approximately twice the frequency of (approximately 20 Hz) and in synchronism with the vibration of the optical fiber strand 3, the vibration of the optical fiber strand 3 was 0.1%. It could be suppressed to less than mm. At this time, the magnitude ΔT of the tension applied by the microvibrating body 16 is 5%, which is 10% or less, as a percentage of the ratio (ΔT / T ₁ ) to the value T ₁ of the normal drawing tension. It was

FIG. 4 shows a second example of an embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

In the optical fiber drawing apparatus of this example, since the tension for vibration damping is applied to the optical fiber strand 3, the fiber vibration detector 12 for detecting the vibration of the optical fiber strand 3 and the fiber vibration are detected. An amplifier 17 that amplifies the detection output of the detector 12, and a calculator 18 that calculates the frequency, amplitude, etc. of the vibration damping tension fluctuation that is applied to the optical fiber strand 3 by using the detection output amplified by the amplifier 17 as an input. A driver 19 for driving the microvibration body 16 formed of a piezoelectric vibrator as a vibration damping tension applying means by the output of the arithmetic unit 18 is used. Other configurations are the same as those in FIG.

In the wire drawing device having such a structure, the detection output of the fiber vibration detector 12 is amplified by the amplifier 17 and input to the calculator 18, which is used for vibration damping to the optical fiber strand 3. Calculates the frequency of tension fluctuation. That is,
The computing unit 18 has a frequency of the vibration fluctuation of the tension applied to the optical fiber strand 3 for damping, and is about 2 of the frequency of the optical fiber strand 3.
The frequency and the amplitude of the vibration fluctuation tension applied to the optical fiber 3 are calculated, and the output of the calculator 18 is output to the driver 1
9 to drive the minute vibrating body 16 composed of a piezoelectric vibrator by the driver 19 and vibrate the take-up roll 10 in the drawing direction, so that the optical fiber element wire 3 is synchronized with the vibration and its frequency is changed. A tension fluctuation for damping is applied in the drawing direction at a frequency almost doubled.

With such a structure, it is possible to automatically set the frequency of the vibration fluctuation tension applied to the optical fiber strand 3 and drive the microvibrating body 16 as the vibration damping tension applying means. Therefore, the vibration of the optical fiber strand 3 can be suppressed by automatic control.

FIG. 5 shows a third example of the embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention. In this example, the take-up rotation speed variable motor 20 which is a drive motor of the take-up machine 9 is used as the vibration damping tension applying means.
Is used.

In the optical fiber drawing apparatus of the present example, in order to apply the vibration damping tension fluctuation to the optical fiber strand 3, the fiber vibration detector 12 for detecting the vibration of the optical fiber strand 3 and the fiber vibration are detected. An amplifier 17 that amplifies the detection output of the detector 12, and a calculator 18 that calculates the frequency, amplitude, etc. of the vibration damping tension fluctuation that is applied to the optical fiber strand 3 by using the detection output amplified by the amplifier 17 as an input. A driver 19 for driving the take-up rotation speed variable motor 20 as the vibration damping tension applying means by the output of the arithmetic unit 18 is used. Other configurations are the same as those in FIG.

In the wire drawing device having such a structure, the detection output of the fiber vibration detector 12 is amplified by the amplifier 17 and input to the calculator 18, and the calculator 18 gives a vibration suppressing signal to the optical fiber strand 3. Calculates the frequency of tension fluctuation. That is,
The computing unit 18 has a frequency of the vibration fluctuation of the tension applied to the optical fiber strand 3 for damping, and is about 2 of the frequency of the optical fiber strand 3.
The frequency and the amplitude of the vibration fluctuation tension applied to the optical fiber 3 are calculated, and the output of the calculator 18 is output to the driver 1
9 and the driver 19 variably controls the rotation speed of the take-up rotation speed variable motor 20 of the take-up machine 9, so that the optical fiber element wire 3 is synchronized with the vibration and its frequency is almost doubled. The frequency changes the tension for damping in the drawing direction.

With such a structure, the frequency of the vibration fluctuation tension applied to the optical fiber strand 3 is automatically set, and the take-up rotation speed of the take-up machine 9 serving as the vibration damping tension applying means is set. The rotational speed of the variable motor 20 can be variably controlled,
Vibration of the optical fiber strand 3 can be suppressed by automatic control.

FIG. 6 shows a fourth example of the embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention. In this example, a winding rotation speed variable motor 23, which is a drive motor of the winding machine 22 that winds the optical fiber strand 3 around the bobbin 21, after the drawing machine 9 is used as the vibration damping tension applying means.

In the optical fiber drawing apparatus of the present example, the optical fiber strand 3 is provided with a vibration damping tension change. Therefore, the fiber vibration detector 12 for detecting the vibration of the optical fiber strand 3 and the fiber vibration detector 12 are provided. An amplifier 17 that amplifies the detection output of the detector 12, and a calculator 18 that calculates the frequency, amplitude, etc. of the vibration damping tension fluctuation that is applied to the optical fiber strand 3 by using the detection output amplified by the amplifier 17 as an input. A driver 19 for driving the winding rotation speed variable motor 23 as the vibration damping tension applying means by the output of the arithmetic unit 18 is used. Other configurations are the same as those in FIG.

In the wire drawing device having such a structure, the detection output of the fiber vibration detector 12 is amplified by the amplifier 17 and input to the calculator 18, which then applies the vibration to the optical fiber strand 3 for damping. Calculates the frequency of tension fluctuation. That is,
The computing unit 18 has a frequency of the vibration fluctuation of the tension applied to the optical fiber strand 3 for damping, and is about 2 of the frequency of the optical fiber strand 3.
The frequency and the amplitude of the vibration fluctuation tension applied to the optical fiber 3 are calculated, and the output of the calculator 18 is output to the driver 1
9 and the driver 19 variably controls the rotation speed of the winding rotation speed variable motor 23 of the winding machine 22,
In synchronization with the vibration, the optical fiber element wire 3 is subjected to a vibration damping tension fluctuation at a frequency of approximately twice the frequency thereof in the drawing direction.

With this structure, the frequency of the vibration fluctuation tension applied to the optical fiber strand 3 is automatically set, and the winding speed of the winder 22 serving as vibration damping tension applying means is automatically set. The rotation speed of the variable motor 23 can be variably controlled, and vibration of the optical fiber strand 3 can be suppressed by automatic control.

FIG. 7 shows a fifth example of the embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

In the optical fiber drawing apparatus of the present example, in order to give the optical fiber strand 3 a vibration damping tension change, the fiber vibration detector 12 for detecting the vibration of the optical fiber strand 3 and the fiber vibration detector 12 are used. An amplifier 17 that amplifies the detection output of the detector 12, and a calculator 18 that calculates the frequency, amplitude, etc. of the vibration damping tension fluctuation that is applied to the optical fiber strand 3 by using the detection output amplified by the amplifier 17 as an input. A driver 19 for driving the microvibration body 16 formed of a piezoelectric vibrator as a vibration damping tension applying means by the output of the arithmetic unit 18 is used. Other configurations are the same as those in FIG. In this example, a micro-vibration body 16 made of a piezoelectric vibrator as a vibration damping tension applying means is attached to a primary die 4, and the piezoelectric vibrator 16 connects the primary die 4 to the optical fiber strand 3.
It is designed to vibrate in the drawing direction.

In the wire drawing device having such a structure, the detection output of the fiber vibration detector 12 is amplified by the amplifier 17 and input to the calculator 18, and the calculator 18 applies the vibration output to the optical fiber strand 3 for damping. Calculates the frequency of tension fluctuation. That is,
The computing unit 18 has a frequency of the vibration fluctuation of the tension applied to the optical fiber strand 3 for damping, and is about 2 of the frequency of the optical fiber strand 3.
The frequency and the amplitude of the vibration fluctuation tension applied to the optical fiber 3 are calculated, and the output of the calculator 18 is output to the driver 1
9 to drive the minute vibrating body 16 composed of a piezoelectric vibrator by the driver 19 to vibrate the primary die 4 in the drawing direction of the optical fiber element wire 3, and the viscosity of the resin in the primary die 4 causes the vibration. Primary dice 4
Is transmitted to the optical fiber element wire 3 through the resin, and the optical fiber element wire 3 is synchronized with the vibration and the tension fluctuation for damping in the drawing direction is applied at a frequency approximately twice the frequency. Is given.

With such a structure, it is possible to automatically set the frequency of the vibration fluctuation tension applied to the optical fiber strand 3 and drive the microvibrating body 16 as the vibration damping tension applying means. Therefore, the vibration of the optical fiber strand 3 can be suppressed by automatic control.

FIGS. 8A, 8B and 8C show the vibration damping tension applying means such as the microvibrating body 16 made of a piezoelectric vibrator in the optical fiber drawing method and apparatus according to the present invention. 3 shows another two examples of tension fluctuation waveforms that are caused to vibrate in synchronization with the vibration of the line 3. Here, FIG. 8A shows a vibration waveform of the optical fiber element wire 3.

FIG. 8B shows an example in which a half wave of a sine wave is used as a tension fluctuation waveform for vibrating the vibration damping tension applying means such as the microvibrating body 16 made of a piezoelectric vibrator.

FIG. 8C shows an example in which a continuous minute pulse train is used as a tension fluctuation waveform for vibrating the vibration damping tension applying means such as the minute vibrator 16 formed of a piezoelectric vibrator.

Since the present invention can be used as a measure against vibration of the optical fiber strand 3, it is not limited to a measure against vibration when the optical fiber is cooled, and is also effective as a measure against vibration when the optical fiber strand 3 vibrates due to a disturbance. Is. For example, when the linear velocity of the optical fiber rises (when the preform is replaced and then started up) or when the bobbin of the winder is continuously replaced, the optical fiber strand vibrates due to fluctuations in tension for damping the optical fiber strand It is also effective as a countermeasure against vibration when a problem occurs.

The constituent features of some of the plurality of inventions described in the specification will be described below.

(1) In an optical fiber drawing device for heating an optical fiber to draw an optical fiber by drawing a preform,
A vibration damping tension imparting means for applying a vibration damping tension variation to the optical fiber strand in a drawing direction, a fiber vibration detector for detecting the vibration of the optical fiber strand, and a detection output of the fiber vibration detector. An optical fiber drawing apparatus comprising an arithmetic unit for calculating a frequency of a vibration damping tension change and a driver for driving the vibration damping tension applying means based on an output of the arithmetic unit.

(2) As the vibration damping tension applying means, a microvibrating body for vibrating a take-up roll for taking the optical fiber strand in the drawing direction is used (1).
The optical fiber drawing apparatus according to.

(3) As the tension imparting means for vibration damping, a variable take-off speed motor of a take-off machine for taking the optical fiber strand is used, and the drawing of the optical fiber is described in (1). apparatus.

(4) The optical fiber drawing according to (1) is characterized in that a variable winding speed motor of a winder for winding the optical fiber strand is used as the vibration damping tension applying means. apparatus.

(5) The optical fiber according to (1) is characterized in that, as the vibration damping tension applying means, a microvibrating body is used for vibrating a die for coating the optical fiber with resin in the drawing direction. Drawing device.

[0067]

In the method of drawing an optical fiber according to the present invention, when vibration of the optical fiber element is generated, the optical fiber element is subjected to vibration damping tension fluctuations in the drawing direction. Vibration of the wire can be suppressed. Therefore, the drawing of the optical fiber is stable, the fluctuation of the outer diameter of the optical fiber can be suppressed, and the quality of the optical fiber can be improved.

Further, in the optical fiber drawing method according to the present invention, the vibration of the optical fiber strand is detected, and the optical fiber strand is synchronized with the vibration so that its frequency is approximately 2
Since the vibration damping tension fluctuation is applied in the drawing direction of the optical fiber strand at a frequency twice, the vibration of the optical fiber strand can be suppressed. Therefore, the drawing of the optical fiber is stable, the fluctuation of the outer diameter of the optical fiber can be suppressed, and the quality of the optical fiber can be improved.

Further, if the tension fluctuation for damping applied to the optical fiber element wire is applied by vibrating the take-up roll that draws the optical fiber element wire in the drawing direction, the optical fiber element wire can be easily controlled. It is possible to give fluctuations in tension for diversion.

Further, when the vibration damping tension variation applied to the optical fiber strand is applied by varying the rotation speed of the drive motor of the take-up machine for pulling the optical fiber strand, the optical fiber strand is applied to the optical fiber strand. The tension fluctuation for damping can be easily applied.

Further, when the vibration damping tension variation applied to the optical fiber strand is applied by varying the rotation speed of the drive motor of the winder for winding the optical fiber strand, the optical fiber strand is subjected to the fluctuation. The tension fluctuation for damping can be easily applied.

Further, when the vibration damping tension variation applied to the optical fiber strand is applied by vibrating the die for coating the optical fiber strand in the drawing direction, the viscosity of the resin in the die causes The vibration of the die is transmitted to the optical fiber wire via the resin, and the vibration fluctuation tension can be easily applied to the optical fiber wire.

Further, in the optical fiber drawing apparatus according to the present invention, vibration damping tension applying means for applying a vibration damping tension variation to the optical fiber wire in the drawing direction, and vibration of the optical fiber wire are detected. A fiber vibration detector, a computing unit for computing the frequency of vibration damping tension fluctuation based on the detection output of the fiber vibration detector, and a driver for driving the damping tension applying means by the output of the computing unit. Since it has, it is possible to drive the vibration damping tension applying means by automatically setting the frequency of the vibration damping tension fluctuation applied to the optical fiber strand by the fiber vibration detector and the calculator. Vibration of the optical fiber strand can be suppressed by control.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first example of an embodiment of a drawing apparatus for carrying out an optical fiber drawing method according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a configuration for applying a vibration damping tension variation to an optical fiber strand at a place of a take-up machine in FIG.

FIG. 3A is a waveform diagram showing vibration of an optical fiber strand,
(B) is a waveform diagram of a vibration damping tension variation applied to the optical fiber strand in order to suppress the vibration of the optical fiber strand.

FIG. 4 is a block diagram showing a main part configuration of a second example of the embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

FIG. 5 is a block diagram showing a main part configuration of a third example of an embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

FIG. 6 is a vertical cross-sectional view showing a fourth example of an embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

FIG. 7 is a vertical cross-sectional view showing a fifth example of the embodiment of the drawing apparatus for carrying out the optical fiber drawing method according to the present invention.

FIG. 8A is a waveform diagram showing vibration of an optical fiber strand,
(B) and (C) are waveform diagrams of two types of damping tension fluctuations applied to the optical fiber strand in order to suppress the vibration of the optical fiber strand.

FIG. 9 is a vertical cross-sectional view showing a drawing apparatus for carrying out a conventional optical fiber drawing method.

[Explanation of symbols]

 1 Preform 2 Heating Furnace 3 Optical Fiber Element 4 Primary Die 5 Primary Curing Furnace 6 Secondary Die 7 Secondary Curing Furnace 8 Optical Fiber Core 9 Pulling Machine 10 Pulling Rolls 11A, 11B First and Second Cooling Unit 12 Fiber vibration detector 13 Rotating shaft 14 Bearing 15 Housing 16 Micro vibrating body (vibration damping tension applying means) 17 Amplifier 18 Operator 19 Driver 20 Variable take-up rotational speed motor (vibration damping tension applying means) 21 Bobbin 22 Winding machine 23 Winding speed variable motor (vibration damping tension applying means)

Claims (7)

[Claims] 1. A method for drawing an optical fiber, wherein a preform is heated to draw an optical fiber element wire, and when the optical fiber element wire vibrates, the optical fiber element wire is used for damping vibration in the drawing direction. A method for drawing an optical fiber, characterized in that tension fluctuation is applied. 2. A method for drawing an optical fiber, wherein a preform is heated and drawn to obtain an optical fiber wire, in which a vibration of the optical fiber wire is detected, and the optical fiber wire is synchronized with the vibration to detect the vibration. A method for drawing an optical fiber, characterized in that a tension variation for damping is applied to the optical fiber element wire in a drawing direction at a frequency approximately twice the frequency. 3. The fluctuation of vibration damping tension applied to the optical fiber strand is given by vibrating a take-up roll for pulling the optical fiber strand in the drawing direction. A method for drawing an optical fiber according to. 4. The fluctuation in vibration damping tension applied to the optical fiber strand is given by varying the rotation speed of a drive motor of a take-up machine that pulls the optical fiber strand. 3. The optical fiber drawing method according to 1 or 2. 5. The vibration fluctuation tension applied to the optical fiber wire is applied by changing the rotation speed of a drive motor of a winder that winds the optical fiber wire. 3. The optical fiber drawing method according to 1 or 2. 6. The vibration fluctuation tension applied to the optical fiber strand is applied by vibrating a die for coating the optical fiber strand with a resin in a drawing direction. A method for drawing an optical fiber according to. 7. An optical fiber drawing apparatus which obtains an optical fiber wire by heating a preform to draw an optical fiber, and a damping tension applying means for applying a vibration fluctuation tension to the optical fiber wire in a drawing direction. A fiber vibration detector for detecting the vibration of the optical fiber strand, a calculator for calculating the frequency of tension fluctuation for damping based on the detection output of the fiber vibration detector, and an output of the calculator And a driver for driving the vibration damping tension applying means.